Fuel feeding device for aircraft



1943- R. AVIGDOR I 2,325,931

FUEL FEEDING DEVICE FOR AIRCRAFT Filed June 21, l94l be entirelystopped.

at such place within thetank it may occur t Patented Aug. 3, 1943 UNITEDSTA S PATENT OFFICE:

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8 Claims.

This application is a continuation-in-part of applicant's priorapplication Serial No. 256,157 illed February 13, 1939, now Patent No.2,263,864. granted November 25, 1941.

This invention relates to. a fuel feeding device for aircraft in whichmeans are provided for counteracting the evaporation of liquid fuel dueto'high altitudes.

The liquid fuel required for the operation of the internal combustionengine of an airplane, is fed to the engine by meansof a pump from oneor more tanks located at suitable places in the airplane. The pump isdriven by an electro-motor which may-be mounted in the casing of thepump or. externally thereto. a

It is a purpose of the invention to locate the pump externally of thefuel. tank so that ready access may be had thereto for repairs orreplacements and at the same time with the inlet of such pump locatednear the bottom of the tank and closely adjacent the return line from .acooling .system for maintainingv the fuel in liquidform at the inlet/ofthe pump.

The fuel tank may be. provided with insulated walls or may consist ofwalls constructed of non-metallic substances.

It has been found in practice that tanks of the above-mentioned type actas heat-accumulators and that the 'fuel within such'tank becomes heatedand accumulates the heat absorbed for a considerable time. Such heatingis a consequence of the sun rays and the outside temperature. Therefore,as soon as an airplane with its fuel heated in such a way ascends to aconsiderable height the fuel in thetank will begin to evaporateand-gasify due to the decreasing air pressure. The result will be thatthe pump can no longer satisfactorily feed the fuel to the engine. Thisis because a blade pump is generally used and the feeding action of sucha. pump will stopas. soonas trapped gases or vapors of the fuel occur inthe f e path of the pump. Furthermore, it is impossible to cool the fuelwithin the tank because of the insulated walls and also because theclimbing speed of airplanes has been so increasedthatthe airplanereaches a considerable height in an exceedingly short time. This causesuncertain feed of the fuel and in such case the feed may Furthermorewhen the fuel within the tank ""is'heated the gases and vapors aretrapped genfuel.

the'fuel supply may be stopped even in the case of a small increase ofthe temperature of the Moreover, Just at the inlet zone of the pump asomewhat reduced pressure is created by -the suction of the pump rotoras compared with the pressure in the surrounding mass of liquid andtherefore evaporation or gasificatlon of the fuel will occur at suchpoint earlier or more intensivelv than throughout the remainder of the.tank. 1

ever, is to take place at a point in 'the vicinity of the inlet of thepun'ip feeding the fuel to the motor.

It is also an object 6: the invention to utilize I the pump which feedsfuel to the engine for feeding fuel to the cooler and in such case. a

.portion of the fuel delivered by the engine feed pump is branched oiland passed through the cooler located outside of the fuel tank. Thereturn flow of such fuel from the'cooler enters the tank in the vicinityof the inlet feed pump.

A further object of the invention is the locatof the motor ing of thecooler at a convenient place on the airplane so as to be subiected'tothe air current. A cooler of this nature need have but relatively smalldimensions since the outside temperature at considerable heights is verylow and then in addition the strong air current caused by the flight ofthe airplane itself produces a strong tion of the engine, the branchingoil of part of the fuel for' circulation through a cooler for coolingthe fuel contents of the tank may be power plant.

It is a further object of the invention to provide a constructionwherein the fuel returning from the cooler in liquid form is directedtowards for circulating the fuel to the cooler is partially Qcompensated by the smaller amount of energy used always necessary to beproduced by the pump. An object of the invention, therefore, is todevice a cooling system which consumes relatively little power.

It is especially advantageous to construct in accordance with theinvention the outlet end of the return conduit so as to form an injector"for the fuel surrounding said return conduit end. In such constructionthe fuel carried along by the injector action is not only cooled butalso urged toward the rotor of the pump. The speed of the cooled fuelleaving the return conduit is then utilized in a special way. A stillfurther object or the invention, there- ;fore, is to provide aconstruction whereby it is possible to effectively .cool in a shorttime. the contents of a fuel tank by circulation so that even in thehottest season and under very strong sun radiation the temperature ofthe fuel is kept so low that no evaporation or gasiflcation can occur.

The invention is shown in the drawing diagrammatically by way'of exampleand the figure illustrates an elevation with parts in section of anembodiment of the invention.

Referring to the drawing the fuel tank of an time. The fuel thereforeflows at a certain speed and at a certain pressure to the rotor of thepump 2 and the advantages referred to above are obtained. The conduit I0for the return flow from the cooler 9 is provided with a special heatinsulating layer It so that the fuel is supplied to the inlet of thefeed pump at the lowest possible temperature.

. It will be noted that the pump utilized in this construction servestwo functions, namely the feeding of the airplane engine and thecirculation in the cooling arrangement. It therefore is not necessary toprovide an additional pump.

With regard to the cooler 9, the coil cooler or a cooler of any othertype may be used to secure .the requisite action.

. fuel tank, a pump unit located externally of such airplane is shown atI and the pump 2 is located externally thereof with its inlet 3 locatedclose to the bottom of the tank I. The fuel is fed by the pump throughthe conduit 5 to the T connection 6 where part of the fuel is fedthrough the conduit 4 to the engine and a portion ofthe fuel is branchedoff through the conduit 8 to the cooler 9; The cooler 9 is mounted on anairplane in such a manner that it is subjected to the air current or isexposed in such a manner that the fuel is effectively cooled. The outletconduit III from the cooler returns the cooled fuel in liquid form tothe tank I and discharges such fuel through the outlet II at a: pointadjacent the inlet 3 of the pump. A strainer may be-pro- 'vided ifdesired at the inlet to the pump. The

motor for operating the pump 2 is shown at I.

I a fuel tank, a cooler having means to facilitate The operation of theconstruction described is'as follows:

The pump 2 feeds fuel in liquid form continu-' of the airplane. and at 8a portion of such fuel' is branched off through the conduit 8 into thecooler 9. In the cooler the warm.fuel coming from the tank I is cooledand flows back through the conduit III into the tank. Part of the fuelleaving the outlet end of the conduit I0 is "mixed with the warm fuel inthe tank I and thereby reduces gradually the temperature of the fuel.

In a relatively short time the total amount of fuel in the tank I hasbeen passed through the cooler 9 and in this way a rapid cooling of thefuel is obtained so that no evaporation or gasiflcation due to the heataccumulating walls of the tank can occur.

In order to utilize the pressure head of the circulating fuel resultingfrom the operation of the pump and the position of the cooler 9, theoutlet end of the return conduit of the fuel is formed as an injector.The outlet end II of the conduit III is located within a tapering hollowmember I1 and together therewith forms an injector. .The fuel leavingthe outlet II draws in the fuel surrounding the injector and carriessuch fuel along towards the pump 2. At the same time the fuel carriedalong by the action of the injector is cooled while the pressure head ofthe return conduit promotes the feed at the same tank the pump of whichconstitutes the motor feed pump and said pump having an inlet connectedto said tank for withdrawing fuel from said tank, a cooler having meansto facilitate heat exchange and located outside said fuel'tank tomaintain the fuel in liquid form, a motor feed conduit connected to saidpump, a conduit connecting the motor feed conduit to said cooler forfeeding to said cooler part of the fuel delivered by the motor feed pumpand an insulated conduit from the cooler to a point adjacent the inletof said feed pump to return the cooled fuel to said feed pump.

2. A fuel feeding device for aircraft comprising heat exchange andlocated outside said tank to maintain the fuel inliquid form, an enginefeed pump located externally of said tankwith its inlet connected tosaid tank for withdrawing fuel from said tank, means for branching off aportion of the fuel delivered by said pump to said cooler and insulatedmeans for returning the fuel cooled by said cooler'to said tank at thevicinity of the inlet of said pump.

' 3. A'fuel feeding device as set forth in claim .2 in which saidinsulated means for returning the fuel cooledby said cooler cooperateswith the pump inlet so as to form a fuel injector.

4. A feed device for readily volatile liquid'fuel for aircraftcomprising a fuel tank, a motor feed pump located externally of saidtank and having its inlet connectedto said tank for withdrawin fuel fromsaid tank, a cooler having means to facilitate heat exchange to insuremaintaining the fuel in liquid form located outside said fuel tank, a.motor feed conduit connected to said pump, a conduit connecting saidmotor 'feed conduit to said cooler for feeding to'said cooler part ofthe fuel delivered by the motor feed pump tank, a motor feed conduitconnected to said pump, a conduit connecting said motor feed conduit tosaid cooler for feeding to said cooler part of the fuel delivered by themotor feed pump and a conduit from said cooler to a point adjacent theinlet of said pump for returning cooled fuel in liquid form to said feedpump, said last-named conduit being insulated.

6. A feeding device for readily volatile liquid fuel for aircraftcomprising a fuel tank, a cooler having means to facilitate heatexchange to insure maintaining the fuel in liquidform located outsidesaid tank, an engine feed pump located externally of said tank with itsinlet connected to said tank for withdrawing fuelfrom' said tank, meansfor branching off a portion of the fuel des livered by said pump to saidcooler and means for returning the fuel cooled by said cooler in liquidform to the vicinity of the inlet 'of said pump.

7. A feed device for readily volatile liquid fuel for aircraftcomprising a fuel tank, a motor feed pump located externally of saidtank with its inlet connected to said tank for withdrawing fuel fromsaid tank, a cooler having means to facilitateheat exchange to insuremaintaining the fuel in liquid form located outside said fuel tank, amotor feed conduit connected to said pump, a conduit connecting saidmotor feed conduit to said cooler for feeding to said cooler part of thefuel delivered by the motor feed pump and a conduit from said cooler toa point adjacent the inlet of said 'pump for returning cooled fuel inliquid form to said fce d pump and said last-named conduit cooper- Ringwith said pump inlet so as to form a fuel injector.

8. A feed device for readily volatile liquid fuel for aircraftcomprising a fuel tank, a motor feed pump located externally of saidtank with its inlet connected to said tank for withdrawing fuel fromsaid tank, a cooler having means to facilitate heat exchange to insuremaintaining the fuel in liquid form located outside said fuel tank, amotor feed conduit connected to said pump, a conduit connecting saidmotor feed conduit to said cooler for feeding to said cooler partof thefuel delivered by the motor feedpump and'a conduit from said cooler to apoint adjacent the inlet of said pump for returning cooled fuel inliquid form to said feed pump and said last-named conduit cooperatingwith said'pump inlet so as to form a fuel injector, said last-namedconduit being heat insuiated. RIFAT AVIGDOR.

